This invention pertains to the art of wheelchairs and, more particularly, to a wheelchair seat assembly that provides self-leveling capabilities to a wheelchair occupant. The invention is particularly applicable to a power wheelchair and will be described with reference thereto. However, it will be appreciated that the invention has broader applications and may be advantageously employed in manual wheelchair environments and applications, related home health care products, or perhaps still other related seat applications.
Wheelchairs are used by people with various infirmities. Those wheelchair occupants that have limited upper body muscle control or suffer from some type of paralysis, for example, are unable to easily balance themselves or compensate for an uneven ground surface over which the wheelchair passes. Because of this impaired balance, wheelchair users are extremely cautious and have a reoccurring fear of losing their balance or control over uneven or sloping terrain. Even when an attendant is available to assist the wheelchair occupant, the inability to control one's balance can be an imposing fear. This fear is heightened when a power wheelchair user, more accustomed to his or her freedom associated with individual control, is then placed in a situation where the ground surface causes momentary instability or loss of balance. Moreover, many surfaces over which the wheelchair traverse are not, in fact, level. Therefore, it is a frequent or common disturbance and concern for the wheelchair occupant.
These same wheelchair users are confined to their chair for substantially all of their waking hours. Commercially available products provide limited pressure relief for the occupant, for example, by changing the orientation of the user or providing specially designed seat cushions to alleviate pressure points. Reclining and tilt-in-space features for wheelchair seats are particular examples of products where the orientation of the wheelchair occupant is altered or modified to provide pressure relief. Typically, though, the recline and tilt-in-space features require an attendant to reposition the seat position relative to the ground. Thus, and even though this provides temporary relief, it requires the assistance of an attendant and is not automatically actuated by the wheelchair occupant.
Thus, a need exists for a wheelchair, and particularly a wheelchair seat, that is responsive to uneven terrain. An additional need exists for ease of adjustment to address pressure relief aside from mere weight shifting by the occupant. Additionally, although the concept is more adaptable to power wheelchairs because of the battery already used to drive the chair, it will be understood that such a feature should be adaptable to an attended wheelchair that has a power supply to provide an automatic or selective self-leveling feature if so desired.